weekly digest implementation
implemented weekly digest emails as a delayed job

* added info about running in README.md
* refactored to be more clear
refactored weekly digest emails as a delayed job
Add staging db config
Cron jobs
Rename messages; create missions; refactor mailers into delayed_jobs
adding API documentation to README
file name correction
merge with staging
initial setup of weekly mailer with whenever gem
uncommenting comments
delete comments on devise.rb, delete inbound_email.rb, undo feature to delete past old emails as background task
Merge pull request #2 from ohmage/weeklyDigest

Weekly digest with whenever scheduler
Messages API, mission setting, some authentication improvements
Mergify! (And comment out weekly updates until ready with the new e-mail template for them.)
Peapod scraper; changing protect_from_forgery to not throw exceptions
Update homepage to remove household_size field
Fix delayed e-mail delivery bug for on boarding e-mail
Update e-mail and URL constants for staging server
Update URL paths for mailers